As I noted in my previous post, the recent announcement by the State Government of proposals to develop up to 35,000 new homes south of Campbelltown at Menangle Park, Mount Gilead and Wilton Junction was very short on detail, particularly in relation to employment strategies and transport infrastructure plans. I suggested some steps to address this including upgrades to the existing rail line, but I also proposed that any extension of the South West Rail Link involve a link to the proposed Greater Macarthur release area. As well as providing access to employment opportunities associated with the proposed airport, such a link could form part of a major outer-Sydney orbital public transport corridors.

Such corridors will become increasingly important not only at the periphery but closer to the CBD as Sydney continues to grow. While many observers including me have passionately debated the merits of the mode and route choices made by the government, it has to be said that most of the missing radial “spokes” of Sydney’s public transport network are either already under construction or are planned to be completed in the next decade. There is still a lot to be done (and a lot of arguments still to be had) in finishing, extending and upgrading these radial corridors and providing the services that run along them, but essentially the government is succeeding both in increasing the capacity of the CBD-focussed network and (to a lesser extent) extending its reach.

This leaves the next big transport challenge that Sydney’s politicians and planners face – the development of orbital links between major residential and employment centres outside the CBD and to these radial corridors.

Why are orbital corridors so important?

Apart from the obvious convenience of providing ways to literally get around the city rather than go through it, orbital links provide a range of planning, employment and environmental benefits. Currently most public transport patronage occurs along the city’s radial corridors; these trips are competitive in time and cost with private vehicle use, especially for trips into the CBD during peak hour. Attempt to move across or between these corridors however and you often get a very different outcome, especially in terms of trip duration.

It is hard enough if there is a nearby orbital connector, as in many cases users still have to start their journey by travelling along a radial corridor to the interchange with the orbital service and then change again at the other end to another radial service. In many parts of Sydney even this isn’t an option, as there are currently few dedicated orbital corridors. There are some orbital bus routes but these are affected by traffic and can be very slow. People who live close to the CBD do have the option of travelling into the city centre on one radial corridor and out again on another, but this is also time-consuming and adds to inner-city congestion.

Further out cars are pretty much essential for orbital trips. This means that attempts to increase levels of employment containment within regions like Western Sydney (ie, maximising jobs within the region for local residents) on equity and environmental grounds can actually have the perverse result of causing a decline in public transport patronage and an increase in vehicle-kilometres as people swap city-bound trains and buses for their own vehicles. This will become an increasingly critical issue as both residential development and jobs head further west, south west and north west.

One answer therefore is to develop a strategy of planning and providing more dedicated orbital public transport corridors. As well as providing a competitive alternative to car use for orbital trips these links also help to support the development of secondary centres outside the CBD. In doing so these links consolidate employment and residential growth near these centres and help to minimise urban sprawl.

Before I examine this approach in detail it’s useful to clarify what the term “orbital public transport corridor” means. Radial corridors are easier to define – they run from the suburbs into the CBD – but orbital ones are a little more problematic. I’ve defined them as dedicated public transport corridors that do not enter the CBD but which join two or more radial corridors and also connect any major centres between these corridors. This definition rules out street-running buses, but does include bus rapid transit (BRT), light rail, heavy rail and metro corridors.

I have also included parts of the existing and planned corridors which start off from the CBD as radial lines but which later turn to take a more orbital path and in doing so cross other radial corridors. In fact these “accidental” corridors form the bulk of Sydney’s public transport orbitals, even though service patterns on these routes are mainly radial focussed.

It’s worth noting that orbital links are common in a number of large overseas cities, with some inland cities including London, Berlin and Moscow providing opportunities to completely circumnavigate their inner cities by metro or heavy rail. Paris has commenced a massive project to construct a fully automated metro line which will encircle Paris, called “Grand Paris Express”. Of course in coastal cities like Sydney a complete circular route around the CBD is usually not possible but there is still potential for partially orbital corridors to link radial routes coming into the city.

Current orbital corridors (2015)The map above shows Sydney’s current orbital corridors as well as the current and planned radial ones (I have used a slightly out-of-date Transport for NSW map as my base and my additions should be regarded as indicative rather than accurate). The orbital links are numbered from the CBD outwards and the first orbital link (no. 1a) is the most recent – the section of the inner west light rail extension that runs more or less north-south between Lewisham West and Dulwich Hill station, though the former interchange requires a 300-metre walk to Lewisham railway station.

The next three are all examples of heavy rail lines which start out as radial rail corridors but then turn “cross country” to also act as orbital lines. The first (2) is the Epping to Chatswood link which connects the main north and North Shore lines as well as major employment and education areas around Macquarie Park and Macquarie University. Then there is the main north line itself (3) which turns northwards at Strathfield, connecting that centre to Epping and ultimately Hornsby where it meets the North Shore line. The next line out (4) is the most problematic in terms of definition – the link the Bankstown line provides between Bankstown, Birrong and the main western line at Lidcombe.

The final orbital rail link (5) is the most interesting in that it is the only dedicated orbital rail service in Sydney. It was created through the construction of a “Y” link at Harris Park between the main western and southern lines, providing the basis for a direct service from Blacktown through Parramatta, Cabramatta (where it interchanges with the Bankstown line), Glenfield (with links to both the East Hills and recently-opened Leppington lines) and Campbelltown.

The furthest out orbital corridors are provided by the bus transitways built in the 1980s. The Liverpool to Parramatta T-Way (6a) can be regarded as an orbital corridor in its entirety, though its express aim is to provide access to and from various employment and other locations along the relatively indirect route rather than act as a connector between the two rail corridors. Of the North West T-Way, only the section (6b) from Blacktown to the interchange at Burns with the Parramatta to Rouse Hill section can technically be regarded as an orbital connector, at least until the North West Metro is completed.

What will be in place by 2025?

Even though I have been a little generous in applying my definition of orbital corridors it is obvious that there are a number of major gaps. Some of these will be addressed over the next ten years or so as a number of major public transport projects are completed. Again these are planned predominantly as radial corridors and services but they will intersect with a number of existing corridors to create or extend orbital connections.

The second map (above) shows my best guess at what infrastructure will be in place by 2025, based as much as possible on Transport for NSW plans and government announcements. I’ve assumed that the Sydney metro will be completed in its entirety from Cudgegong Road and Rouse Hill through the CBD and on to Bankstown, though I have made no assumptions about its extension beyond Bankstown or the previously-planned link to Hurstville. I’ve also assumed that the CBD and South East Light Rail will have been completed and that there will be some form of bus rapid transit along Parramatta Road and to the northern beaches.

Second-guessing the Western Sydney light rail network is more problematic as currently four routes have been shortlisted for consideration to be the first section to be constructed. Two however seem to be the frontrunners (Parramatta to Macquarie Park and Parramatta to Sydney Olympic Park and Strathfield/Burwood) and I have therefore assumed that both will be built in the next ten years.

The result is likely to be a modest but useful expansion in the orbital corridor framework. Some of the corridors shown on the map will remain speculative until final plans are announced and construction is complete but I think it is safe to make some educated guesses. Starting from the CBD and working out again, the first addition (no. 1b) will be an extension of the “orbital section” of the inner west light rail line, resulting not from any changes to that line but instead from the construction of the proposed Parramatta Road BRT. This means that there is the potential for an interchange between this planned bus corridor and the light rail at Taverners Hill.

The next addition (4a) is a likely outcome of the completion of the Sydney metro to Bankstown. No plans have been announced for the rest of the Bankstown line but a likely result is some sort of restructuring of the Bankstown-Birrong-Lidcombe-Cabramatta section. I’ve assumed retention of the current heavy rail service on the map but conversion to light rail is another option; either way this section of track would effectively become an orbital corridor, connecting between the heavy rail main south and western lines and the metro at Bankstown.

The completion of the light rail line proposed between Parramatta and Strathfield via Olympic Park would also turn the current Lidcombe to Olympic Park rail line (4b) into an orbital connector, a virtual extension of 4a. Likewise, the completion of the metro to Rouse Hill effectively makes the whole of the North West T-Way into an orbital, with connections to Parramatta and Blacktown on the main West rail line and Kellyville and Rouse Hill on the metro line (6b and 6c).

Finally if both the Western Sydney light rail lines identified as priorities are constructed, they will certainly cement Parramatta’s role as Sydney’s second CBD and as a key interchange between orbital and radial corridors in Sydney’s west. While their primary role will be as radial links based on Parramatta rather than the Sydney CBD, the link to Macquarie Park (7) would also act as a critical orbital link, providing access for western and south western residents to the Epping-Macquarie Park employment and education corridor and vice versa.

In my next post I’ll look at some suggestions for orbital connections beyond 2025, as well as some of the service and operational issues involved.